JP6663618B2 - Accelerator and particle beam irradiation device - Google Patents

Description

  The present invention relates to an accelerator for accelerating ions such as protons and carbon, and a particle beam irradiation apparatus including the accelerator.

  An apparatus for obtaining an ion beam of arbitrary energy in a circular accelerator is described in Patent Document 1. Patent Document 1 describes that "a beam guide made of a superconductor is installed behind a deflector, and this beam guide is made movable along with the deflector along the orbital rotation radius direction of the particles". .

JP-A-1-289100

  Particle beam irradiation apparatuses are roughly classified into a particle beam irradiation apparatus having a synchrotron as an accelerator and a particle beam irradiation apparatus having a cyclotron as an accelerator.

  Among them, the particle beam irradiation device having a cyclotron includes, for example, an ion source, a cyclotron, a beam transport system, a rotating gantry, and an irradiation device. The cyclotron has a vacuum vessel constituted by a pair of opposed iron cores having a circular cross section, a high-frequency accelerator, and an extraction electromagnet. The beam transport system is connected to the exit of the cyclotron where the extraction electromagnet is located.

  In a particle beam irradiation apparatus having a cyclotron, ions emitted from an ion source (for example, cations or heavy ion such as carbon, which is heavier than protons such as carbon) are incident on the center of the cross section of the iron core of the cyclotron, and are subjected to high-frequency acceleration. Accelerated by the device. The accelerated ion beam spirals from the center of the iron core toward the inner side surface of the return yoke, and is emitted to the beam transport system by an extraction electromagnet provided at the periphery of the iron core. The emitted ion beam passes through the beam transport system and is irradiated from the irradiation device to the affected part of the patient's cancer on the treatment table.

  In such a general cyclotron, a deflector for taking out is set near the outer periphery of the accelerating electrode in order to take out accelerated particles. Then, particles accelerated to the maximum energy by the deflector are taken out, and particles of arbitrary energy are obtained using an energy absorber (degrader) installed outside the circular accelerator. Therefore, it is necessary to provide an extra configuration in order to extract a beam of an arbitrary energy, and it is difficult to control a beam energy with high accuracy, so that it is difficult to extract a beam of a predetermined energy.

  Further, Patent Document 1 described above describes a circular accelerator for obtaining an ion beam of arbitrary energy without using this degrader. However, the mechanism for extracting a beam described in Patent Document 1 requires a beam guide made of a superconductor, a deflector that moves mechanically, and a beam deflector. For this reason, since a large-scale moving device in a vacuum is required, there is a problem that the device becomes very large and complicated.

  An object of the present invention is to provide an accelerator capable of easily extracting a beam of any energy over a wide range without using a large-scale moving device, and a particle beam irradiation device including the accelerator. .

In order to solve the above problem, for example, a configuration described in the claims is adopted.
The present invention includes a plurality of means for solving the above-mentioned problems. For example, an ion source, an accelerating unit for accelerating an ion beam extracted from the ion source, and a circular orbit of the ion beam are mentioned. the provided magnetic pole for generating isochronous field that form a local magnetic field generating unit disposed within the orbit, and a changing unit for changing the trajectory of the ion beam at an incident trajectory adjustment portion, said The magnetic pole is located at a position whose center is deviated to the extraction position side of the ion beam, forms the orbit such that an orbital aggregation region is generated in the orbit, and the ion source is located near the center of the magnetic pole. Characterized by being arranged in

  ADVANTAGE OF THE INVENTION According to this invention, the beam of arbitrary energy can be taken out easily and over a wide range, without using a complicated and large-scale apparatus.

It is a figure showing the whole particle beam irradiation device composition of the present invention. FIG. 2 is a side view schematically showing the circular accelerator according to the first embodiment of the present invention. FIG. 3 is a plan view schematically illustrating a plane of the circular accelerator illustrated in FIG. 2. FIG. 4 is a perspective view schematically showing magnetic poles of the circular accelerator shown in FIG. 3. FIG. 4 is a cross-sectional view schematically illustrating the angle adjuster illustrated in FIG. 3. FIG. 4 is a plan view illustrating an example of an ion beam trajectory when the angle adjuster that rotates the ion source illustrated in FIG. 3 is used. FIG. 7 is a diagram illustrating a relationship between a rotation angle and an extraction energy when the ion source illustrated in FIG. 6 is rotated. FIG. 4 is a cross-sectional view schematically illustrating a local magnetic field generation unit illustrated in FIG. 3. FIG. 9 is a plan view illustrating an example of an orbit changing electrode in the circular accelerator according to the second embodiment of the present invention. FIG. 13 is a plan view illustrating an example of a trajectory changing electromagnet in the circular accelerator according to the third embodiment of the present invention.

  Embodiments 1-3, which are preferred embodiments of the accelerator and the particle beam irradiation device of the present invention, will be described below with reference to the drawings. First, the concept of the accelerator having the most suitable configuration as the accelerator of the present invention will be described.

  The present inventors have conducted various studies to realize an accelerator that can continuously extract an ion beam like a cyclotron and can extract an ion beam with different energy like a synchrotron.

  The present inventors first paid attention to the interval between the beam orbits of the ion beam orbiting in the vacuum vessel of the cyclotron (the mutual beam orbits in the radial direction of the vacuum vessel) so that the beam could be easily extracted. Interval). Increasing the interval between the beam orbits, that is, increasing the interval (turn separation) between the beam orbits, leads to an increase in the diameter of the vacuum vessel and an increase in the size of the cyclotron. Also, in a general cyclotron, a concentric beam orbit is drawn in a vacuum vessel, and it is difficult to secure high-energy turn separation, so that it is difficult to efficiently emit each ion beam having a different energy. Met.

  Here, in the cyclotron, there is a beam passing region (plane) in which the radius gradually increases in a spiral shape, and the ion source is installed near the center of this region so that ions enter the orbit. The present inventors move the beam incident point present at the center of the beam passing area in the cyclotron to the beam extraction port side formed on the outer periphery of the beam passing area, that is, move the beam incident point at the center of the beam passing area. It was considered to move the beam into the orbit from a position shifted toward the beam extraction port. As a result, the interval between the beam orbits formed in the vacuum vessel between the incident position of the ions to be injected into the vacuum vessel and the beam extraction port becomes closer (orbital convergence area is formed), and the beam is extracted. At a position 180 ° opposite to the port, it was found that the distance between the beam orbits formed in the vacuum vessel could be widened, contrary to the distance between the beam incident point and the beam extraction port.

  The present inventors have created a new accelerator capable of efficiently extracting each ion beam having a different energy by applying such a concept of the beam orbit.

  An embodiment of the present invention which can be suitably applied to the accelerator newly created by the present inventors described above will be described below with reference to the drawings.

<Example 1>
First Embodiment An accelerator and a particle beam irradiation apparatus according to a first embodiment of the present invention will be described with reference to FIGS. First, the overall configuration of the particle beam irradiation apparatus and the configuration of a related apparatus will be described with reference to FIG. FIG. 1 is a diagram showing an overall configuration of a particle beam irradiation apparatus to which the present invention relates.

  1, the particle beam irradiation apparatus 100 includes an accelerator 20, a beam transport system 60, an irradiation device 70, a treatment table 40, and a control device 50.

  In the particle beam irradiation apparatus 100, the ions generated by the ion source 4 are accelerated by an accelerator 20 to form an ion beam. The accelerated ion beam is emitted from the accelerator 20 and transported to the irradiation device 70 by the beam transport system 60. The transported ion beam is shaped by the irradiation device 70 so as to conform to the shape of the affected part, and is irradiated on the target of the patient 45 lying on the treatment table 40 by a predetermined amount.

  The operation of each device and equipment in the particle beam irradiation device 100 including the accelerator 20 is controlled by the control device 50.

  Next, the structure of the accelerator 20 will be described with reference to FIGS. FIG. 2 is a schematic side view of a circular accelerator to which the present invention is applied, and FIG. 3 is a schematic plan view of FIG. FIG. 4 is a perspective view schematically showing a magnetic pole. FIG. 5 is a cross-sectional view schematically showing the angle adjuster. FIG. 6 is a plan view showing an example of the trajectory of the ion beam when an angle adjuster for rotating the ion source is used. FIG. 7 is a diagram illustrating the relationship between the rotation angle and the extraction energy when the ion source is rotated. FIG. 8 is a cross-sectional view schematically showing the local magnetic field generation unit.

  As shown in FIGS. 2 and 3, accelerator 20 includes ion source 4, high-frequency electrode (accelerator) 3, magnetic pole 1, local magnetic field generator 2, vacuum vessel 10, annular coil 5, And a take-out septum 11.

  Inside the vacuum vessel 10, a high-frequency electrode 3 having a hollow inside is disposed symmetrically in the portion of the magnetic pole recess 1c, and a high-frequency power supply 15 applies a high frequency from the outside. The high-frequency electrode 3 accelerates the ion beam extracted from the ion source 4 using the electric field generated by the high frequency.

  The vacuum vessel 10 is arranged so as to be sandwiched by the magnetic poles 1. The vacuum vessel 10 forms one vacuum vessel as a whole and forms a magnetic circuit to generate a main magnetic field 41 in the magnetic pole gap 43. The vacuum container 10 is a non-magnetic material.

The annular coil 5 is provided on the atmosphere side of the vacuum vessel 10 and is a coil for generating a main magnetic field 41 (B ₀ ) in the magnetic pole gap 43 between the magnetic poles 1 by the magnetic poles 1. The toroidal coil 5 may be a coil made of a normal conducting material or a coil made of a superconducting material.

  As shown in FIG. 4, the magnetic pole 1 has magnetic pole convex portions 1a and 1b and a magnetic pole concave portion 1c, and has a left-right symmetric structure and a vertically asymmetric structure when viewed from above. The circulating frequency of the ion beam is, for example, 19.82 megahertz (MHz), and the magnetic pole 1 is set to generate an isochronous magnetic field that makes one round of the same time with any energy. For example, the magnetic field acting on the beam along the beam trajectory is formed by the magnetic pole convex portions 1a and 1b so that the concave portion has a low magnetic field and the convex portion has a high magnetic field. The shapes and heights of the magnetic pole protrusions 1a and 1b are set to directions and intensities that suppress the divergence of the ion beam in the direction of the magnetic pole gap 43 and in the circumferential direction. The magnetic pole 1 is a magnetic material, for example, iron. The surface of the magnetic pole 1 facing the magnetic pole gap 43 has a symmetrical shape. The center of the magnetic pole formed by the magnetic pole protrusions 1a and 1b and the magnetic pole recess 1c is located at a position deviated from the center of the magnetic pole 1 to the beam extraction position 44, and the ion source 4 is disposed near the center. Due to such a biased arrangement, the magnetic pole 1 generates an orbital consolidation area 18 in the orbit.

  In this embodiment, four magnetic pole projections 1a and 1b are used, but there is no limitation as long as the number of poles is two or more. Although not shown, a trim coil for fine adjustment of the magnetic field is provided on the magnetic pole protrusions 1a and 1b, and the trim coil current can be adjusted so as to ensure isochronism and stable betatron oscillation. is there.

  As described above, the “isochronous magnetic field” in the present invention means that even if the energy of the accelerated ion beam increases and the radius of the beam orbit around which the ion beam circulates increases, the ion beam makes one round. This means a magnetic field whose time does not change.

  The “circular orbit” means a plurality of annular orbits until ions emitted from the ion source 4 are extracted from the extraction position 44.

  As shown in FIG. 2, the ion source 4 is disposed in the magnetic pole 1. The high frequency power supply 15 applies a high frequency to the high frequency electrode 3, and the ion source 4 generates an ion between the ground electrode 21 and the high frequency electrode 3. Ions generated in the source 4 are extracted into the accelerator 30.

  As shown in FIG. 5, in order to change the trajectory of the ion beam from the time of extraction from the ion source 4 according to the extraction energy of the ion beam, the trajectory of the ion beam is changed to the incident trajectory. An angle adjuster 31 is attached as a changing unit to be changed in the adjusting unit 6.

  The angle adjuster 31 includes a motor 31a and a mounting shaft 31b, and adjusts the extraction angle of ions extracted from the ion source 4 by rotating the ion source 4 mounted on the mounting shaft 31b by the motor 31a by a predetermined angle. . The mounting shaft 31b of the ion source 4 has a vacuum sealing structure, and is configured to maintain a vacuum in the vacuum vessel 10.

  Around the ion source 4, the trajectory immediately after the extraction is controlled as an area for changing the trajectory of the ion beam at a timing after the extraction from the ion source 4 according to the extraction energy of the ion beam, and the extraction is easy. An incident trajectory adjustment unit 6 that changes the trajectory so as to be defined as follows. The incident trajectory adjustment unit 6 means a range within one round after being extracted from the ion source 4.

  FIG. 6 shows an example of how the incident trajectory adjusting unit 6 changes the trajectory of the ion beam by rotating the ion source 4.

  As described above, an electric field is generated between the ground electrode 21 and the high-frequency electrode 3. An ion beam is extracted from the ion source 4 by the generated electric field, and accelerated by the electric field generated by the high-frequency electrode 3. At this time, in the present embodiment, the angle of the ion beam extracted by the angle between the high-frequency electrode 3 and the extraction surface of the ion source 4 is adjusted by rotating and fixing the ion source 4 to a predetermined angle by the angle adjuster 31. It can be changed to any value. For example, when the extraction angle of the ion beam is 0 degree, the trajectory 7a becomes the pre-change trajectory 7a shown in FIG. 6, and the trajectory 7b becomes the post-change trajectory 7b by rotating the ion source 4.

  FIG. 7 shows an example of the analysis result of the extraction energy of the beam energy and the rotation angle of the ion source 4 when the acceleration condition by the high-frequency electrode 3 is fixed and used together with the local magnetic field generator 2.

As shown in FIG. 7, for example, by rotating the ion source 4 so that the extraction angle is set to 0.17 radian, a beam of 70 megaelectron volts (MeV) can be extracted. Also, an 85 MeV beam is extracted by rotating the ion source 4 so that the extraction angle is 0.215 radian, and a 95 MeV beam is extracted by rotating the ion source 4 so that the extraction angle is 0.24 radian. Can be. As shown in FIGS. 2 and 8, the local magnetic field generation unit 2 is disposed in the orbit of the magnetic pole recess 1 c 180 ° opposite to the side where the orbital consolidation area 18 in which the beam orbit 7 is aggregated is formed. ing. This local magnetic field generating unit 2 is arranged to face with a space that passes through the ion beam in the pole gaps 43 direction, on a part of the orbit, taking out the magnetic field for extracting the ion beam (B _m) Generate. The local magnetic field generator 2 can be formed, for example, by sandwiching it with an annular coil or two or more independent wires, and the position and the number are determined according to the number of energy to be extracted.

  The ion beam deflected by the magnetic field generated by the local magnetic field generator 2 is transported to the extraction position 44. The ion beam transported to the extraction position 44 is extracted outside the magnetic pole 1 by the extraction septum 11. The extraction septum 11 operates in the same manner using a magnetic field or an electric field.

  The accelerator 20 configured as described above operates as follows.

  The ion beam extracted from the ion source 4 and entered from the center of the magnetic pole protrusions 1a and 1b makes a spiral motion by the main magnetic field 41 formed by the magnetic pole protrusions 1a and 1b and the magnetic pole recess 1c. Each time it passes through the high-frequency electrode 3 during the helical movement, it is accelerated by the electric field generated by the high-frequency electrode 3, the energy increases, the radius of rotation increases, and the orbit moves in the vacuum vessel 10. At this time, the shapes and heights of the magnetic pole protrusions 1a and 1b are set to directions and intensities so as to suppress the divergence of the beam in the direction of the magnetic pole gap 43 and in the circling direction. It is set to make one round. The magnetic field acting on the beam along the beam trajectory has a low magnetic field in the concave portion and a high magnetic field in the convex portion due to the magnetic pole convex portions 1a and 1b. In this way, the strength of the magnetic field along the beam orbit and the average value of the magnetic field along the orbit are proportional to the relativistic gamma factor (γ factor) of the beam. Betatron oscillation stably occurs within the orbit plane of the beam and in a direction perpendicular to the orbit plane, while keeping the beam constant.

  The trajectory of the circulating beam is deflected by the local magnetic field 42 generated by the local magnetic field generation unit 2 that has reached the extraction energy. As a result, the orbiting beam deviates from the orbit and moves to the extraction position 44. The direction of the local magnetic field 42 is determined in the same direction as the main magnetic field 41 or in the opposite direction depending on the energy. Since the trajectory of the incident beam near the ion source 4 is changed by rotating the ion source 4, even if the intensity of the local magnetic field 42 is reduced, an ion beam having a predetermined beam energy can be easily extracted. Further, since the orbiting ion beam orbits are concentrated at the extraction position 44, deflection and extraction toward the extraction position 44 can be performed with a smaller local magnetic field 42 than the non-aggregated orbit.

  The beam movement adjustment to the extraction position 44 has been described using both the local magnetic field generation unit 2 and the incident trajectory adjustment unit 6; however, each may be used alone. For example, the magnetic field that can be generated by the local magnetic field generating unit 2 is 0.02 Tesla (T) when a commonly used wire is used, and the incident trajectory adjusting unit 6 is used to compensate for the insufficient displacement.

  By extracting a beam using a magnetic field in this manner, energy can be switched at high speed without using a sliding portion. If a plurality of local magnetic field generators 2 are arranged from the center for energy extraction to the outer peripheral direction, energy can be switched without moving the local magnetic field generator 2. The extraction of the ion beam can be performed in a half circle, but there is no problem if the ion beam is extracted a plurality of times. Thus, extraction can be performed with less local magnetic field strength and adjustment of the incident trajectory.

  Next, effects of the present embodiment will be described.

  In the above-described first embodiment of the present invention, in the particle beam irradiation apparatus 100 including the accelerator 20 and the irradiation apparatus 70 for irradiating the ion beam emitted from the accelerator 20, the accelerator 20 includes the ion source 4, the ion source 4, A high-frequency electrode 3 for accelerating an ion beam extracted from a source 4; a magnetic pole 1 for generating an isochronous magnetic field formed to generate a circular orbit of the ion beam; and a local electrode arranged in the circular orbit. The apparatus includes a magnetic field generator 2 and an angle adjuster 31 that changes the trajectory of the ion beam in the incident trajectory adjuster 6. The accelerator 20 is configured to change the trajectory of the ion beam at a timing after the extraction from the ion source 4 according to the extraction energy of the ion beam by the angle adjuster 31.

  Therefore, the ion source 4 can be appropriately adjusted so that the ion beam has a predetermined energy, and the ion beam can be extracted at a higher speed and without using a large-scale apparatus as compared with the related art. I have. Further, since the ion beam is extracted by the local magnetic field generator 2, even if the intensity of the local magnetic field 42 generated by the local magnetic field generator 2 is reduced, an ion beam having a predetermined beam energy can be easily extracted.

  Further, since the magnetic pole 1 is formed so as to generate the orbital consolidation area 18 in the orbital orbit, the orbiting orbiting ion beam orbital is condensed at the extraction position 44, so that the locality is smaller than that of the non-consolidated orbital. The beam can be deflected to the beam extraction position 44 by the magnetic field 42, and the extraction becomes very easy. In particular, since the interval between the beam orbits in the orbital consolidation area 18 is narrower than before, even if the energy of the ion beam extends over a wide range, a predetermined magnetic field or the like generated by the local magnetic field generator 2 can be used. The ion beam of energy can be stably and easily deflected toward the beam extraction position 44 on the trajectory aggregation area 18 side.

  Further, by using the angle adjuster 31 for rotating the ion source 4 as a changing unit for changing the trajectory of the ion beam in the incident trajectory adjusting unit 6, the trajectory of the ion beam can be changed with a simple configuration. , An ion beam having a predetermined beam energy can be obtained. Further, since there is no insert in the orbit and does not hinder the orbit, highly accurate beam control can be performed.

  Further, since the ion source 4 is accommodated in the magnetic pole 1, the structure of the angle adjuster 31 can be simplified.

  Furthermore, since the trajectory of the beam is changed when the ions are extracted from the ion source 4, the trajectory can be changed stably and reliably.

<Example 2>
Second Embodiment An accelerator and a particle beam irradiation apparatus according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The same applies to the following embodiments. FIG. 9 is a schematic cross-sectional view of the configuration of the circular accelerator according to the present embodiment in which the orbit changing electrode is disposed in the incident orbit adjusting unit 6.

  As shown in FIG. 9, in the accelerator of the present embodiment, the angle adjustment of the first embodiment is performed in order to change the trajectory of the ion beam at a timing after the extraction from the ion source 4 according to the extraction energy of the ion beam. As a changing unit for changing the trajectory of the ion beam in the incident trajectory adjusting unit 6 instead of the detector 31, trajectory changing electrodes 32a and 32b disposed opposite to the ion beam immediately after being extracted from the ion source 4 have magnetic poles. A portion corresponding to the concave portion 1c is disposed so as to face and be parallel to the vertical direction. The trajectory is changed by deflecting the ion beam immediately after passing through the high-frequency electrode 3 once by the orbit changing electrodes 32a and 32b. When, for example, a positive potential is applied to the trajectory changing electrode 32a and a negative potential that is the reverse potential of the trajectory changing electrode 32a is applied to the trajectory changing electrode 32b, the ion beam having a positive charge is changed from the pre-change trajectory 7a shown in FIG. It can be changed to the track 7b. The trajectory can be changed in the opposite direction by changing the polarity.

  It should be noted that there is no problem even if the orbit changing electrodes 32a and 32b are installed in the high-frequency electrode 3.

  The orbit changing electrodes 32a and 32b may be installed at any week, but the energy increases with each lap and the voltage required for deflection increases. Positions within are most appropriate.

  Other configurations and operations are substantially the same as those of the accelerator and the particle beam irradiation device of the first embodiment described above, and the details are omitted.

  In the accelerator and the particle beam irradiation apparatus according to the second embodiment of the present invention, substantially the same effects as those of the accelerator and the particle beam irradiation apparatus according to the first embodiment described above can be obtained.

  In addition, as a changing unit that changes the trajectory of the ion beam in the incident trajectory adjusting unit 6, the trajectory changing electrodes 32a and 32b that generate an electric field for changing the trajectory of the ion beam extracted from the ion source 4 are used. The trajectory can be changed at a high speed by changing ON / OFF and the intensity of the trajectory, and the time required for the change can be shortened.

  Further, since the incident trajectory adjusting unit 6 is within the range of one revolution after being extracted from the ion source 4, the trajectory can be deflected before the voltage required for deflection increases, and the trajectory can be changed more easily. be able to.

<Example 3>
Third Embodiment An accelerator and a particle beam irradiation apparatus according to a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a schematic cross-sectional view of the configuration of the circular accelerator according to the present embodiment in which the orbit changing electromagnet is disposed in the incident orbit adjustment unit 6.

  As shown in FIG. 10, in the accelerator of the present embodiment, the trajectory of the ion beam is incident in order to change the trajectory of the ion beam at a timing after the extraction from the ion source 4 according to the extraction energy of the ion beam. As a changing unit to be changed in the trajectory adjusting unit 6, an annular trajectory changing electromagnet 33 arranged opposite to the ion beam immediately after being extracted from the ion source 4 is replaced with the angle adjuster 31 of the first embodiment. It is arranged at a portion corresponding to the concave portion 1c. The orbit changing electromagnets 33 are arranged facing each other with a space in the direction of the magnetic pole gap 43. The trajectory is changed by deflecting the ion beam immediately after passing through the high-frequency electrode 3 once by the orbit changing electromagnet 33 from the ion source 4. The magnetic field generated by the orbit changing electromagnet 33 is generated in a direction perpendicular to the plane of FIG. The polarity of the generated magnetic field changes according to the energy of the extracted ion beam.

  The position of the orbit changing electromagnet 33 may be set at any week, but the energy increases with each orbit and the magnetic field required for deflection increases. A position within one round is most appropriate.

  Other configurations and operations are substantially the same as those of the accelerator and the particle beam irradiation device of the first embodiment described above, and the details are omitted.

  In the accelerator and the particle beam irradiation apparatus according to the third embodiment of the present invention, substantially the same effects as those of the accelerator and the particle beam irradiation apparatus according to the first embodiment described above can be obtained.

  In addition, as a changing unit that changes the trajectory of the ion beam in the incident trajectory adjusting unit 6, the trajectory changing electromagnet 33 that generates a magnetic field for changing the trajectory of the ion beam extracted from the ion source 4 is used to turn on the magnetic field. The trajectory can be changed at a high speed by changing / OFF and the intensity, and the time required for the change can be shortened.

  Further, since the incident trajectory adjusting unit 6 is within the range of one revolution after being extracted from the ion source 4, the trajectory can be deflected before the magnetic field required for deflection increases, and the trajectory can be changed more easily. be able to.

<Others>
Note that the present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described above. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of one embodiment can be added to the configuration of another embodiment. Also, for a part of the configuration of each embodiment, it is possible to add, delete, or replace another configuration.

DESCRIPTION OF SYMBOLS 1 ... Magnetic pole 1a, 1b ... Magnetic pole convex part 1c ... Magnetic pole concave part 2 ... Local magnetic field generation part 3 ... High frequency electrode (acceleration part)
4 ... Ion source 5 ... Annular coil 6 ... Injection orbit adjustment unit 7 ... Beam orbit 7a ... Orbit before change 7b ... After change orbit 10 ... Vacuum container 11 ... Septum 15 ... High frequency power supply 20 ... Accelerator 21 ... Ground electrode 31 ... Angle adjuster (change part)
31a: motor 31b: mounting shafts 32a, 32b: orbit changing electrode (change part)
33 ... orbit changing electromagnet (change part)
40 ... treatment table 41 ... main magnetic field 42 ... local magnetic field 43 ... magnetic pole gap 44 ... takeout position 45 ... patient 50 ... control device 60 ... beam transport system 70 ... irradiation device 100 ... particle beam irradiation device

Claims (8)

An ion source;
An accelerating unit for accelerating an ion beam extracted from the ion source,
A magnetic pole that generates the isochronous field that form the orbit of the ion beam,
A local magnetic field generator arranged in the orbit,
A changing unit that changes the trajectory of the ion beam in an incident trajectory adjusting unit ,
The magnetic pole is located at a position whose center is deviated to the extraction position side of the ion beam, and forms the orbit such that an orbit aggregation region is generated in the orbit,
The accelerator according to claim 1, wherein the ion source is disposed near a center of the magnetic pole . The accelerator according to claim 1,
The accelerator, wherein the change unit is an angle adjuster that rotates the ion source. The accelerator according to claim 2,
The accelerator, wherein the ion source is accommodated in the magnetic pole. The accelerator according to claim 1,
The accelerator, wherein the changing unit is an electrode that generates an electric field for changing the trajectory of the ion beam extracted from the ion source. The accelerator according to claim 1,
The accelerator, wherein the changing unit is an electromagnet that generates a magnetic field for changing the trajectory of the ion beam extracted from the ion source. The accelerator according to claim 1,
The accelerator according to claim 1, wherein the incident trajectory adjustment unit is within a range of one revolution after being extracted from the ion source. An accelerator according to claim 1;
An irradiation device for irradiating the ion beam emitted from the accelerator. A particle beam irradiation device. An ion source;
An accelerating unit for accelerating an ion beam emitted from the ion source,
A magnetic pole that generates the isochronous field that form the orbit of the ion beam,
A local magnetic field generator arranged in the orbit,
The magnetic pole is located at a position whose center is deviated to the extraction position side of the ion beam, and forms the orbit such that an orbit aggregation region is generated in the orbit,
The ion source is disposed near a center of the magnetic pole,
An accelerator, wherein the trajectory of the ion beam is changed at a later timing from the time of extraction from the ion source in accordance with the extraction energy of the ion beam.

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